Organizations such as on-line retailers, Internet service providers, search providers, financial institutions, universities, and other computing-intensive organizations often conduct computer operations from large scale computing facilities. Such computing facilities house and accommodate a large amount of server, network, and computer equipment to process, store, and exchange data as needed to carry out an organization's operations. Typically, a computer room of a computing facility includes many server racks. Each server rack, in turn, includes many servers and associated computer equipment.
Computing systems typically include a number of components that generate waste heat. Such components include printed circuit boards, mass storage devices, power supplies, and processors. For example, some computers with multiple processors may generate 250 watts of waste heat. Some known computing systems include a plurality of such larger, multiple-processor computers that are configured into rack-mounted components, and then are subsequently positioned within a rack system. Some known rack systems include 40 such rack-mounted components and such rack systems will therefore generate as much as 10 kilowatts of waste heat. Moreover, some known data centers include a plurality of such rack systems.
Computing systems mounted in a rack may include one or more fans mounted in individual computing systems to cool components of the computing systems. Such arrangements may lead to inefficiencies because the computing systems include a large number of relatively small fans that are inefficient when compared to larger fans. Some racks may include larger rack-level fans used to cool computer systems mounted in the racks. In some racks, rack-level fans may be controlled based on rack-level inputs without regard to temperature variations between computing devices mounted in the rack. In some control arrangements control of rack-level fans may not allow different ones of the rack-level fans to operate at different speeds. Such arrangements may lead to inefficiencies in cooling computing systems mounted in a rack. For example, the rack-level fans may provide surplus cooling to computer systems in the rack that are operating at lower temperatures than other computer systems in the rack that are operating at hotter temperatures. In another example, the rack-level fans may provide adequate cooling to computer systems operating under normal conditions and temperatures but not provide adequate cooling to computer systems that are operating at higher temperatures.
While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the drawings and detailed description thereto are not intended to limit the invention to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the present invention as defined by the appended claims. The headings used herein are for organizational purposes only and are not meant to be used to limit the scope of the description or the claims. As used throughout this application, the word “may” is used in a permissive sense (i.e., meaning having the potential to), rather than the mandatory sense (i.e., meaning must). Similarly, the words “include,” “including,” and “includes” mean including, but not limited to.